A need presently exists for a means by which low cost, highly filled, highly flame resistant, low smoking articles can be produced by filament winding, hand lay-up, reaction injection molding, or pultrusion. A particular need presently exists for a means by which low cost, highly flame resistant, low smoking pipes, ducts, fittings, and related articles can be produced by filament winding or by hand lay-up.
Filament winding processes are commonly used to produce pipes and numerous other articles In a filament winding process, one or more continuous fiber strands are wound, under tension, around a prepared core (e.g., a pipe mandrel). Before or during the winding operation, the continuous fiber strand(s) is (are) impregnated with a thermosetting resin composition. Typically, the impregnation of the continuous fiber strand(s) is accomplished by pulling the fiber strand(s) through a resin bath prior to winding the strand(s) around the prepared core. After the impregnated fiber strand(s) has (have) been wrapped around the core, the thermosetting resin is allowed to harden (i.e., to cure). If desired, or if necessary, the filament wound product can be heated in order to accelerate the resin curing process.
Hand lay-up processes are commonly used in the art for producing pipes, pipe fittings, and numerous other articles. In a hand lay-up process, strips or sheets of fabric (e.g., a glass cloth or mat) are saturated (i.e., impregnated) with a thermosetting resin composition and are then wrapped around a prepared core (e.g., a pipe mandrel). The impregnation of the fabric strips or sheets is typically accomplished by applying the thermosetting resin composition to the fabric strips or sheets using a roller-type resin applicator. The impregnated fabric strips or sheets are wrapped around the prepared core until a desired thickness is obtained. After the impregnated fabric strips or sheets have been wrapped around the prepared core, the thermosetting resin composition is allowed to harden (i.e., to cure). If desired, or if necessary, the hand lay-up product can be heated in order to accelerate the resin curing process.
In most cases, the filament winding and hand lay-up processes used heretofore have required the use of relatively low viscosity resin compositions (i.e., compositions having viscosities of less than about 600 centipoise). The use of compositions having viscosities exceeding about 600 centipoise hinders fiber strand and fabric wetting (i.e., impregnation) and thus results in the production of filament wound products and hand lay-up products having inadequate resin content. Additionally, when used for filament winding, compositions having viscosities in the range of from about 600 to about 1000 centipoise create drag problems which result in fiber strand fraying and breakage. Similar problems are experienced when compositions having viscosities exceeding about 600 centipoise are used for pultrusion.
Due to the necessity of using low viscosity resin compositions in filament winding and hand lay-up processes, the production of fire-resistant filament wound articles and fire-resistant hand lay-up articles has heretofore been difficult and/or costly. As is known in the art, relatively inexpensive fire-resistant compression molded articles have been produced using thermosetting resin compositions which contain large amounts of aluminum trihydrate (ATH) filler. However, when an amount of ATH filler sufficient to provide desirable flame resistance properties is added to a thermosetting resin composition, the viscosity of the resin composition is increased tremendously.
In order to use a highly ATH filled thermosetting resin composition for filament winding or for hand lay-up, it has generally been necessary heretofore to substantially increase the temperature of (i.e., to heat) the resin composition during the fiber strand or fabric impregnation process. However, this approach is costly. Further, the use of a high temperature resin composition creates a substantial safety hazard for workers.
It is also noted that some filament wound articles and hand lay-up articles have been produced heretofore using non-heated, highly ATH filled epoxy resins. However, in most cases, these compositions have included certain reactive diluents which copolymerize with the epoxy resins to yield polymer products which exhibit low chemical resistance.
To produce fire-resistant articles by filament winding or hand lay-up, those skilled in the art have typically used relatively expensive halogenated thermosetting resins. Through the use of these resins, articles having excellent flame spread index values of 25 or less have been produced. Unfortunately, however, these resins give off large quantities of sooty black smoke.
BYK.RTM.-W995 (manufactured by BYK-Chemie, 524 South Cherry Street, P. 0. Box 5670, Wallingford, Conn. 06492) has been used in low-shrink polyester compression molding compositions (i.e., sheet molding compositions, bulk molding compositions, and dense molding compositions) as a wetting and dispersing agent. A low-shrink polyester compression molding composition will typically contain at least one thermoplastic component. The thermoplastic component operates to reduce the shrinkage of, and to improve the surface quality and mechanical properties of, compression molded articles produced from the low-shrink composition. Unfortunately, it is typically difficult to incorporate substantial quantities of fillers (e.g., calcium carbonate, chopped glass fiber, ATH, and the like) in low-shrink compression molding compositions due to the disparate wetting properties of the polyester and thermoplastic components of these compositions. However, these wetting problems are reportedly alleviated by the addition of BYK.RTM.-W995. Specifically, the addition of BYK.RTM.-W995 to a low-shrink polyester compression molding composition increases the amount of filler which can be added to the composition at a given composition viscosity.
BYK.RTM.-W995 is composed of about 48 parts by weight of a phosphated polyester, about 25 parts by weight of a naphtha and light aromatic solvent, about 25 parts by weight of 1-methoxy-2-propanol acetate, and up to about 2 parts by weight of phosphoric acid. The phosphated polyester component of the BYK.RTM.-W995 composition is a saturated polyester having acidic groups. BYK.RTM.-W995 has a boiling range (solvent) of from about 295.degree. to about 365.degree. F., a vapor density (air=1) of &gt;1, a vapor pressure at 20.degree. C. of about 4 mm Hg, a density (DIN 51757) at 20.degree. C. in the range of from about 1.000 to about 1.050 g/cm.sup.3, a flash point (Setaflash) (DIN/ISO 3679) of about 44.degree. C., an acid value in the range of from about 46 to about 58 mg KOH/g, and a nonvolatile matter value (DIN/ISO 53216 -A, 10 mins. -150.degree. C./302.degree. F.) in the range of from about 50 to about 54%. BYK.RTM.-W995 is described in the publication entitled "BYK.RTM.-W995 Wetting and Dispersing Agent for Low-Shrink SMC, BMC, and DMC," the entire disclosure of which is incorporated herein by reference. BYK.RTM.-W995 is further described in the publication entitled "Provisional Technical Data Sheet BYK.RTM.-W995," the entire disclosure of which is also incorporated herein by reference. Each of these publications is available from BYK-Chemie USA, 524 South Cherry Street, P.O. Box 5670, Wallingford, Conn. 06492.